Methylated Counterparts Research Articles

Methylation and Demethylation of Emerging Contaminants Changed Bioaccumulation and Acute Toxicity in Daphnia magna.

Contaminants of emerging concern (CECs) in the environment undergo various transformations, leading to the formation of transformation products (TPs) with a modified ecological risk potential. Although the environmental significance of TPs is increasingly recognized, there has been relatively little research to understand the influences of such transformations on subsequent ecotoxicological safety. In this study, we used four pairs of CECs and their methylated or demethylated derivatives as examples to characterize changes in bioaccumulation and acute toxicity in Daphnia magna, as a result of methylation or demethylation. The experimental results were further compared to quantitative structure-activity relationship (QSAR) predictions. The methylated counterpart in each pair generally showed greater acute toxicity in D. magna, which was attributed to their increased hydrophobicity. For example, the LC50 values of methylparaben (34.4 ± 4.3 mg L-1) and its demethylated product (225.6 ± 17.3 mg L-1) differed about eightfold in D. magna. The methylated derivative generally exhibited greater bioaccumulation than the demethylated counterpart. For instance, the bioaccumulation of methylated acetaminophen was about 33-fold greater than that of acetaminophen. In silico predictions via QSARs aligned well with the experimental results and suggested an increased persistence of the methylated forms. The study findings underline the consequences of simple changes in chemical structures induced by transformations such as methylation and demethylation and highlight the need to consider TPs to achieve a more holistic understanding of the environmental fate and risks of CECs.

Spin-state energetics and magnetic anisotropy in penta-coordinated Fe(III) complexes with different axial and equatorial ligand environments.

The penta-coordinated trigonal-bi-pyramidal (TBP) Fe(III) complex (PMe2Ph)2FeCl3 shows a reduced magnetic anisotropy in its intermediate-spin (IS) state as compared to its methyl-analog (PMe3)2Fe(III)Cl3. In this work, the ligand environment in (PMe2Ph)2FeCl3 is systematically altered by replacing the axial -P with -N and -As, the equatorial -Cl with other halides, and the axial methyl group with an acetyl group. This has resulted in a series of Fe(III) TBP complexes modelled in their IS and high-spin (HS) states. Lighter ligands -N and -F stabilize the complex in the HS state, while the magnetically anisotropic IS state is stabilized by -P and -As at the axial site, and -Cl, -Br, and -I at the equatorial site. Larger magnetic anisotropies appear for complexes with nearly degenerate ground electronic states that are well separated from the higher excited states. This requirement, largely controlled by the d-orbital splitting pattern due to the changing ligand field, is achieved with a certain combination of axial and equatorial ligands, such as -P and -Br, -As and -Br, and -As and -I. In most cases, the acetyl group at the axial site enhances the magnetic anisotropy compared to its methyl counterpart. In contrast, the presence of -I at the equatorial site compromises the uniaxial type of anisotropy of the Fe(III) complex leading to an enhanced rate of quantum tunneling of magnetization.

Influence of methylation and demethylation on plant uptake of emerging contaminants

Contaminants of emerging concern (CECs) as well as their transformation products (TPs) are often found in treated wastewater and biosolids, raising concerns about their environmental risks. Small changes in chemical structure, such as the addition or loss of a methyl group, as the result of methylation or demethylation reaction, may significantly alter a chemical’s physicochemical properties. In this study, we evaluated the difference in accumulation and translocation between four CECs and their respective methylated or demethylated derivatives in plant models. Suspended Arabidopsis thaliana cell culture and wheat seedlings were cultivated in nutrient solutions containing individual compounds at 1 mg/L. The methylated counterparts were generally more hydrophobic and showed comparative or greater accumulation in both plant models. For example, after 1 h incubation, methylparaben was found in A. thaliana cells at levels two orders of magnitude greater than demethylated methylparaben. In contrast, the demethylated counterparts, especially those with the addition of a hydroxyl group after demethylation, showed decreased plant uptake and limited translocation. For example, acetaminophen and demethylated naproxen were not detected in the shoots of wheat seedlings after hydroponic exposure. Results from this study suggest that common transformations such as methylation and demethylation may affect the environmental fate of CECs, and should be considered to obtain a more comprehensive understanding of risks of CECs in the environment.

Petrology and organic geochemistry of the Baishaping and Damaidi Devonian cutinitic liptobioliths, west of the Kangdian Uplift, China

Devonian cutinitic liptobiolith is a special type of coal formed during the early evolutionary stage of land plants. The Baishaping and Damaidi Devonian coals are notable for their distinct papery, sheet-like texture, and unusually high cutinite content (>50%), belonging to typical cutinitic liptobiolith. They are bituminous coals and have a suppressed vitrinite reflectance. Compared with typical type III kerogen, these liptobioliths are characterized by extremely high yields of volatile matter and high hydrogen contents owing to their enhanced cutinite contents. As indicated by pyrolysis and elemental analysis results, the Devonian cutinitic liptobioliths are dominated by type I-II kerogens and have an excellent potential to generate liquid hydrocarbons. The Baishaping cutinitic liptobioliths are mainly composed of ribbon-like thick-walled cutinites, with small amounts of thin-walled type. Vitrinite is only present in trace amounts and is dominated by telinite. Meanwhile, the Damaidi Devonian coals are primarily composed of ribbon-like thin-walled cutinites, followed by collotelinites which are usually sandwiched by cutinites. The different petrological characteristics of the Baishaping and Damaidi liptobioliths might indicate a structural variation in the coal-forming plant cuticles and two distinct coal-forming conditions. The molecular biomarkers in the Devonian coals are mainly composed of C 18 –C 20 tetracyclic diterpenoids, which are assumed to be the dominant soluble constituent of the Devonian land-plant cuticles and might have played an important role in early land plant radiation. Other molecules include aromatic tetracyclic diterpenoids, 3–5 ring polycyclic aromatic hydrocarbons and their methylated counterparts, and C 16 - and C 18 -monocarboxylic acids. n -Alkanes are present only in small amounts. The molecular composition of the cutinite-rich coals is unexpected, because cuticular waxes are one of the most important sources of n -alkanes. In general, the petrology and geochemistry of the Devonian cutinitic liptobiolith indicate a distinct structure and composition for the early land-plant cuticles, which is significantly different from that of the plant cuticles since Carboniferous. Devonian cutinitic liptobioliths are of great interest because of their unique petrography, geochemistry, coal-forming plants, and oil-prone potential. Studies on this unique coal type provide a better understanding of coal-forming plants, paleoenvironment, paleoclimate, and early land-plant evolution in the Devonian.

Enantioselective Synthesis of Secondary β-Trifluoromethyl Alcohols via Catalytic Asymmetric Reductive Trifluoroalkylation and Diastereoselective Reduction.

Fluorinated motifs are frequently encountered in drugs and agrochemicals. Incorporating fluorine-containing motifs in drug candidates for lead optimization in pharmaceutical research and development has emerged as a powerful tool. The construction of molecules that feature a trifluoromethyl (CF3-) group on a stereogenic carbon has accumulated broad research efforts. Unlike its well-explored, biologically active methyl counterpart, asymmetric construction of β-trifluoromethylated alcohols bearing adjacent stereocenters still remains elusive. Through retrosynthetic analysis, we posited that followed by sequential reduction of carbonyl, the initial construction of chiral α-trifluoromethylated ketones could render the desired product in a facile, one-pot fashion. Herein, we developed the first example of nickel-catalyzed asymmtric reductive cross-coupling trifluoroalkylation of acyl chlorides for enantioselective synthesis of diverse α-trifluoromethylated ketones. The one-pot reduction of these α-trifluoromethylated ketones furnished corresponding alcohols bearing β-CF3-substituted stereogenic carbons with excellent diastereoselectivity and complete enantioselective retention. High yields/enantioselectivity, mild conditions, and good functional group compatibility are shown in the system. Utilities of the method are also illustrated by applying asymmetric, late-stage trifluoroalkylation of biologically active complex molecules, revealing tremendous potential for development of CF3-containing chiral drugs.

Identifying critical parameters for extraction of carnosine and anserine from chicken meat with high voltage pulsed electric fields and water

Carnosine (β-alanyl-L-histidine) and its methylated counterpart anserine (β-alanyl-1-methylhistidine) are important functional dipeptides found in various vertebrates' tissues. In this study, we identified the critical parameters of pulsed electric fields (PEF), coupled to mechanical pressing, followed by incubation in water up to 240 min for the extraction of these bioactive dipeptides from chicken meat. We show that PEF improves the kinetics of anserine and carnosine release to water by 7 to 53%, compared to the same water extraction process without PEF when the incubation time is below 120 min. A fractional factorial design showed that the incubation time in the water, after PEF pretreatment, had the most significant effect on dipeptides extraction. The maximum achieved total protein yield was 15.5 mg gfresh weight(FW)-1 after 120 min incubation in water. The maximum carnosine extraction yield was 7.48 mg gFW−1 with a maximum anserine extraction yield of 3.05 mg gFW−1. The specific energy yield of extraction of protein, carnosine, and anserine was 488.16 mg J−1, 39.43 mg J−1, and 131.63 mg J−1 respectively. The developed method is scalable and could be further explored to extract bioactive compounds from animal tissues.

Binding Methylarginines and Methyllysines as Free Amino Acids: A Comparative Study of Multiple Host Classes**

Methylated free amino acids are an important class of targets for host‐guest chemistry that have recognition properties distinct from those of methylated peptides and proteins. We present comparative binding studies for three different host classes that are each studied with multiple methylated arginines and lysines to determine fundamental structure‐function relationships. The hosts studied are all anionic and include three calixarenes, two acyclic cucurbiturils, and two other cleft‐like hosts, a clip and a tweezer. We determined the binding association constants for a panel of methylated amino acids using indicator displacement assays. The acyclic cucurbiturils display stronger binding to the methylated amino acids, and some unique patterns of selectivity. The two other cleft‐like hosts follow two different trends, shallow host (clip) following similar trends to the calixarenes, and the other more closed host (tweezer) binding certain less‐methylated amino acids stronger than their methylated counterparts. Molecular modelling sheds some light on the different preferences of the various hosts. The results identify hosts with new selectivities and with affinities in a range that could be useful for biomedical applications. The overall selectivity patterns are explained by a common framework that considers the geometry, depth of binding pockets, and functional group participation across all host classes.

Influence of the Number, Nature and Position of Methyl Posttranscriptional Modifications on Nucleobase Stacking in RNA.

DFT calculations are employed to quantify the influence of the presence, number, nature, and position of posttranscriptional methylation on stacking strength of RNA bases. We carry out detailed potential energy scans of the variation in stacking energies with characteristic geometrical parameters in three categories of forty stacked dimers - canonical base homodimers (N||N), methylated base homodimers (mN||mN) and heterodimers of canonical bases and methylated counterparts (N||mN). Our analysis reveals that neutral methylation invariably enhances the stacking of bases. Further, N||mN stacking is stronger than mN||mN stacking and charged N||mN exhibit strongest stacking among all dimers. This indicates that methylations greatly enhance stacking when dispersed in RNA sequences containing identical bases. Comparison of stacks involving singly- and doubly-methylated purines reveal that incremental methylation enhances the stacking in neutral dimers. Although methylation at the carbon position of neutral pyrimidine dimers greatly enhances the stacking, methylation on the 5-membered ring imparts better stacking compared to methylation on the 6-membered ring in adenine dimers. However, methylation at the ring nitrogen (N1 ) provides better stacking than the amino group (N2 ) in guanine dimers. Our results thus highlight subtle structural effects of methylation on RNA base stacking and will enhance our understanding of the physicochemical principles of RNA structure and dynamics.

Using Laboratory Investigations to Aid the Identification of Small Aromatic Molecules in Water-Containing Astrophysical Ices

Monocyclic aromatic hydrocarbons such as benzene, toluene and xylene are thought to play an important role as precursors to the formation of polycyclic aromatic hydrocarbons (PAHs) and their methylated counterparts in a range of astrophysical environments. Benzene has been detected in two carbon rich objects and models have predicted that it could also be present in the interstellar medium (ISM). It has hence been speculated that small aromatic molecules are present in molecular clouds in the ISM, although they have not been detected to date. If they are present in the ISM, they are likely to exist in water-ice dominated icy mantles on the surface of dust grains.We present a laboratory study of benzene, toluene and two xylene isomers (ortho- and para-xylene) in the presence of water ice on a carbonaceous model dust grain surface (highly oriented pyrolytic graphite, HOPG). Temperature programmed desorption (TPD) shows how the desorption of the molecules is affected by the presence of water ice. The importance of these data for astrophysical situations is demonstrated by the use of TPD-derived kinetic parameters to generate a simple model of desorption in dense molecular clouds on an astrophysical timescale. Since benzene, toluene and xylene have not been detected in water-dominated icy mantles to date, desorption has been simulated in a range of different water-containing environments to show the different behaviour expected depending on ice composition. The simulations demonstrate how future observations of aromatic molecules in dense molecular clouds at known temperatures could reveal which environments the molecules are in. Data from these experiments are also used to predict the behaviour of other, larger, aromatic molecules such as PAHs. Reflection absorption infrared spectroscopy (RAIRS) is also used to record the infrared spectra of the small molecules in different water ice configurations. These spectra can be used to aid identification of these icy aromatics in future observations, such as those that will be possible with the James Webb Space Telescope (JWST). In all cases, spectra of mixed ices consisting of the aromatic molecule and amorphous water ice show evidence of interactions between the water ice and the aromatic species.

Epigenetic regulation of TLR2‐mediated periapical inflammation

To determinethe methylation pattern of TLR2 gene promoter and its association with the transcriptional regulation of periapical inflammatory and angiogenic responses in symptomatic and asymptomatic forms of apical periodontitis. In this cross-sectional study, apical lesions were obtained from volunteers with asymptomatic apical periodontitis (AAP) (n=17) and symptomatic apical periodontitis (SAP) (n=17) scheduled for tooth extraction, and both total RNA and DNA were extracted. DNA was bisulfite-treated, a region of CpG island within the TLR2 gene was amplified by qPCR and the products were sequenced. Additionally, the mRNA expression of TLR2, TLR4, IL-6, IL-12, TNFalpha, IL-23, IL-10, TGFbeta, VEGFA and CDH5 was analysed by qPCR. The data were analysed with chi-square tests, Mann-Whitney or unpaired t-tests, and Spearman´s correlation; variable adjustments were performed using multiple linear regression (P<0.05). TLR2 depicted a hypomethylated DNA profile at the CpG island in SAPwhen compared with AAP, along with upregulated expression of TLR2, with pro-inflammatory cytokines IL-6 and IL-23, and the angiogenesis marker CDH5 (P<0.05). TLR2 methylation percentage negatively correlated with mRNA levels of IL-23 and CDH5 in apical periodontitis. Lower methylation frequencies of single CpG dinucleotides -8 and -10 localized in close proximity to nuclear factor κB (NFκB) binding within the TLR2 promoter were identified in SAP versus AAP (P<0.05). Finally, unmethylated -10 and -8 single sites demonstrated up-regulation of IL-23, IL-10 and CDH5 transcripts compared to their methylated counterparts (P<0.05). TLR2 gene promoter hypomethylation was linked to transcriptional activity of pro-inflammatory cytokines and angiogenic markers in exacerbated periapical inflammation. Moreover, unmethylated single sites in close proximity to NFκB binding were involved in active transcription of IL-23, IL-10 and CDH5.

Isotopically enriched n-alkan-2-ones with even chain predominance in a torbanite from the Sydney Basin, Australia

n-Alkan-2-ones (methyl ketones) ranging from C14 to C31, were recovered from the polar fraction of an extract of a torbanite from the Sydney Basin, Australia. There was a very slight even-over-odd predominance between C20 and C24n-alkan-2-ones, together with remarkably high contents of the C24, C26 and C28 homologues. A range of C16 to C28 macrocyclic alkanes, as well as their corresponding methylated counterparts (C19–C24), was also detected in the saturate fraction obtained after molecular sieve treatments. Due to the relatively high contents of the n-alkan-2-ones and macrocyclic alkanes, we were able to carry out GC–irMS analysis to determine the δ13C values of specific compounds. The even-numbered n-alkan-2-ones from C24 to C28 were significantly 13C-enriched, compared to the other n-alkan-2-ones, which had similar isotopic values to the macrocyclic alkanes. The majority of the n-alkan-2-ones detected here probably had the same algal source as the macrocyclic alkanes, which is likely to be lipids and algaenan of the green microalga Botryococcus braunii. However, the distribution and 13C enrichment of C24, C26 and C28n-alkan-2-ones indicates that an additional source must be present.

Terminal modulation of asymmetrical D−A−D−π furan-containing diketopyrrolopyrrole chromophores for intramolecular charge transfer properties

Three furan-based diketopyrrolopyrrole (DPP) chromophores have the same D−A−D structure and various tetraphenylethylene, pyrene and dibenzothiophene tails with intramolecular donor-acceptor spacers. Different π-extended chromophores show different intramolecular charge transfer properties. Furthermore, according to UV–Vis and emission spectral studies, dyes F1–F3 exhibit aggregation-caused quenching (ACQ) in tetrahydrofuran aqueous solutions. Interestingly, dyes F1 and F3 show aggregation-induced emission (AIE) behaviors in DMSO/toluene mixtures, while pyrene-functionalized DPP dye F2 still has ACQ character. It is noted that a contour plot is firstly carried out to be better understood the AIE and ACQ phenomena. Moreover, the energy gaps for the methyl counterpart of dyes F1–F3 are 2.30, 2.29 and 2.35 eV, respectively, which indicate that introducing asymmetrical D−A−D−π furan-containing DPP structures can reduce the HOMO–LUMO gaps easily and rapidly. In addition, a computational and experimental investigation has been provided, including theoretical and optical energy gaps for full comparison.

Identification of phenyldibenzothiophenes in coals and the effects of thermal maturity on their distributions based on geochemical data and theoretical calculations

All four phenyldibenzothiophene (PhDBT) isomers were unequivocally identified in coals for the first time by the co-injection of authentic standards and comparison of the retention indices with those reported in previous studies. Based on density functional theory (DFT) calculations, the relative thermodynamic stability order of the phenyldibenzothiophene isomers (PhDBTs) was determined to be 3-PhDBT > 2-PhDBT > 4-PhDBT > 1-PhDBT. All PhDBT isomers were observed in a suite of coals from the Junggar and Ordos basins, and the effects of thermal maturity on their distributions were systematically investigated. Based on geochemical data and theoretical calculations, two phenyldibenzothiophene maturity indicators, i.e., PhDR1 (2-PhDBT/4-PhDBT) and PhDR2 ((2-PhDBT + 3-PhDBT)/4-PhDBT), are proposed. For high maturity coals (≥0.96 %Ro), PhDR1 and PhDR2 increase gradually with increasing thermal maturity. Two preliminary calibrations of these parameters against measured %Ro were made: %Rc = 0.60 × PhDR1 + 1.00 (≥1.00 %Ro) and %Rc = 0.30 × PhDR2 + 1.00 (≥1.00 %Ro). Compared to their corresponding methylated counterparts, phenyldibenzothiophenes are particularly useful as molecular markers of maturity at higher levels of thermal stress and provide a molecular assessment for sedimentary rocks containing types II and III kerogens where few biomarker parameters are available. PhDBTs in coals are likely to be generated during diagenesis/catagenesis as intermediate products in the formation of more condensed heterocyclic polycyclic aromatic compounds, such as triphenyleno[1,12-bcd]thiophene and benzobisbenzothiophenes, which were detected in the highly mature samples. This study broadens the current understanding of the occurrence, distribution, geochemical significance, and origin of phenyldibenzothiophenes in sedimentary organic matter.

Effects of Substitutions on the Biodegradation Potential of Benzotriazole Derivatives

Fourteen benzotriazole derivatives were subjected to microcosm tests to study the influence of substitutions on their biodegradation potential. Methylated, nitrated, carboxylated, and propionated bezotriazoles, a heterocyclic triazole, as well as methylated benzimidazoles, were introduced to activated sludge and soil enrichment cultures as the only carbon source. Some of the enrichment cultures were derived from airport soils that had been previously contaminated with aircraft deicing fluids and subsequently enriched with the commercially significant corrosion inhibitor methylbenzotriazole. The 5-methylbenzotriazole and only the carboxylated derivatives were degraded by soil or activated sludge biomass regardless of acclimation conditions. Radiotracer studies of [U-14C] 5-methylbenzotriazole, and [U-14C] 5-carboxybenzotriazole confirmed that relatively high concentrations (25mg L-1) of these derivatives can be completely mineralized in relatively short time frames by microbial consortia regardless of prior exposure. Observations suggested that the growth yield on these compounds is likely low. Biodegradation patterns suggested that carboxylated benzotriazole derivatives are more readily biodegradable than their more popular methylated counterparts.

Interplay between 4-Hydroxy-3-Methyl-2-Alkylquinoline and N-Acyl-Homoserine Lactone Signaling in a Burkholderia cepacia Complex Clinical Strain.

Species from the Burkholderia cepacia complex (Bcc) share a canonical LuxI/LuxR quorum sensing (QS) regulation system named CepI/CepR, which mainly relies on the acyl-homoserine lactone (AHL), octanoyl-homoserine lactone (C8-HSL) as signaling molecule. Burkholderia ambifaria is one of the least virulent Bcc species, more often isolated from rhizospheres where it exerts a plant growth-promoting activity. However, clinical strains of B. ambifaria display distinct features, such as phase variation and higher virulence properties. Notably, we previously reported that under laboratory conditions, only clinical strains of the B. ambifaria species produced 4-hydroxy-3-methyl-2-alkylquinolines (HMAQs) via expression of the hmqABCDEFG operon. HMAQs are the methylated counterparts of the 4-hydroxy-2-alkylquinolines (HAQs) produced by the opportunistic human pathogen Pseudomonas aeruginosa, in which they globally contribute to the bacterial virulence and survival. We have found that unlike P. aeruginosa’s HAQs, HMAQs do not induce their own production. However, they indirectly regulate the expression of the hmqABCDEFG operon. In B. ambifaria, a strong link between CepI/CepR-based QS and HMAQs is proposed, as we have previously reported an increased production of C8-HSL in HMAQ-negative mutants. Here, we report the identification of all AHLs produced by the clinical B. ambifaria strain HSJ1, namely C6-HSL, C8-HSL, C10-HSL, 3OHC8-HSL, 3OHC10-HSL, and 3OHC12-HSL. Production of significant levels of hydroxylated AHLs prompted the identification of a second complete LuxI/LuxR-type QS system relying on 3OHC10-HSL and 3OHC12-HSL, that we have named CepI2/CepR2. The connection between these two QS systems and the hmqABCDEFG operon, responsible for HMAQs biosynthesis, was investigated. The CepI/CepR system strongly induced the operon, while the second system appears moderately involved. On the other hand, a HMAQ-negative mutant overproduces AHLs from both QS systems. Even if HMAQs are not classical QS signals, their effect on AHL-based QS system still gives them a part to play in the QS circuitry in B. ambifaria and thus, on regulation of various phenotypes.

Photo-physical and structural studies of some synthesized arylazoquinoline dyes

This study presents the spectral and structure characteristics of seven azoquinoline dyes with different substituents and their new methylated counterparts for the first time, where some compounds are newly synthesized. The solvatochromic, tautomeric, halochromic, and dichroic behavior of the compounds were studied by electronic spectroscopy in various media. The different types of media were ordinary, multifunctional, and ordered liquids. The experiments were extended to include under acidic or basic conditions. The orientational behavior of the azo dye-doped liquid crystals was studied, and it was established that the azo form is the main species in high polar anisotropic media. The multi-parameter polarity scales were used to correlate the spectral data. Influence of acid and base on the absorption spectra of the dyes was also examined. Ionization constants for these dyes were determined in ethanol-water media. As a result, at the high dye concentrations, the intermolecular hydrogen bonding is more stable than the intra-molecular hydrogen bond, and therefore, the azo form is the main species in concentrated solutions. In order to provide more details, time-dependent density functional theory (TD-DFT) calculations were carried out for the representative models.

Investigation into the ring-substituted polyanilines and their application for the detection and adsorption of sulfur dioxide

It has been demonstrated in this study that the substituents on the monomer aniline benzene ring are able to introduce the significant differences to the resulting polyaniline tm)s collective properties. We systematically evaluated the structural perturbation effects of two substituents (methyl and methoxy) of aniline monomer through the electrochemical method. Our results showed that the methoxy group induces the less structural perturbation than the methyl counterpart, because of its partial double bond restriction. The morphologies are different for the polyaniline and the ring-substituted polyanilines, in which substituted polyanilines feature the larger porosities with the addition of these side groups. The influential effects of the methoxy side group have been further illustrated and amplified by its superior sensing performance towards the environmentally-significant sulfur dioxide gas, evaluated through the construction of the quartz crystal microbalance (QCM)-based gas sensor with these polyaniline materials. The as-constructed gas sensor tm)s sensitivity, selectivity and stability in terms of its SO2 responses have been evaluated in details. The methoxy-substituted polyaniline was tested to show the unique gas sensing properties for the sulfur dioxide at the low concentrations (50•250ppm) and function as the adsorbing material at the high concentrations (500•1250ppm). Thus it can be used both as sensing material as well as a novel filter and/or storage reservoir for the removal of sulfur dioxide pollutant from the environments.

DFT investigation of the reaction mechanism for the guanidine catalysed ring-opening of cyclic carbonates by aromatic and alkyl-amines

The bifunctional activity (base/H-bond donor) of TBD allows understanding its higher efficiency compared to its methyl counterpart (MTBD) for the aminolysis of cyclic carbonates by amines.

A novel pollution pattern: Highly chlorinated biphenyls retained in Black-crowned night heron (Nycticorax nycticorax) and Whiskered tern (Chlidonias hybrida) from the Yangtze River Delta

Contamination of organochlorine pesticides (OCPs), polychlorinated diphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and their methylated counterparts (MeO-PBDEs) were determined in Black-crowned night heron (Nycticorax nycticorax) and Whiskered tern (Chlidonias hybrida) from two drinking water sources, e.g. Tianmu lake and East Tai lake in Yangtze River Delta, China. A novel PCBs contamination pattern was detected, including 11% and 6.9% highly chlorinated biphenyls (PCBs with eight to ten chlorines) in relation to total PCB concentrations in the Black-crowned night heron and Whiskered tern eggs, respectively. The predominating OCPs detected in the present study were 4,4′-DDE, with concentration range 280–650 ng g−1 lw in Black-crowned night heron and 240–480 ng g−1 lw in Whiskered tern, followed by β-HCH and Mirex. 6-MeO-BDE-90 and 6-MeO-BDE-99 are the two predominant congeners of MeO-PBDEs whereas 6-OH-BDE-47 contributes mostly to the OH-PBDEs in both species. Contamination level was considered as median or low level compared global data.

Hydroxylated and methoxylated polybrominated diphenyl ethers in long-tailed ducks (Clangula hyemalis) and their main food, Baltic blue mussels (Mytilus trossulus × Mytilus edulis).

Long-tailed ducks (Clangula hyemalis) that breed in northern Europe and western Siberia and commonly winter in the Baltic Sea, are threatened by a significant population decrease. The ducks are, by primarily feeding on Baltic blue mussels (Mytilus trossulus × Mytilus edulis) while wintering in the Baltic Sea, potentially subjected to high levels of toxic hydroxylated polybrominated diphenyl ethers (OH-PBDEs). To assess long-tailed ducks exposure to polybrominated phenols (PBPs), polybrominated anisoles (PBAs), hydroxylated polybrominated diphenyl ethers (OH-PBDEs), their methylated counterparts (MeO-PBDEs) and polybrominated diphenyl ethers (PBDEs), livers of ten long-tailed ducks wintering in the Baltic Sea were analysed. Pattern and levels of analytes in long-tailed ducks (liver) and blue mussels sampled in March and May at nine sites in the Baltic Sea were compared. The geometric mean concentration (ng/g l.w.) in livers of long-tailed ducks and Baltic blue mussels were: Σ(2)PBPs: 0.57 and 48; Σ(2)PBAs: 0.83 and 11; Σ(7)OH-PBDEs: 6.1 and 45; Σ(7)MeO-PBDEs: 3.8 and 69; Σ(7)PBDEs: 8.0 and 7.2, respectively. Based on an estimated daily intake of 450 g fresh blue mussel meat, long-tailed ducks daily dietary intake of brominated substances while foraging in the Baltic Sea in March-May was estimated to; 390 ng Σ(2)PBPs, 90 ng Σ(2)PBAs, 370 ng Σ(7)OH-PBDEs, 590 ng Σ(7)MeO-PBDEs and 59 ng Σ(7)PBDEs. The low levels of PBPs, PBAs, OH-PBDEs and MeO-PBDEs in the long-tailed duck livers compared to blue mussel, despite a continuous daily intake, suggest that these compounds are poorly retained in long-tailed ducks.